1. Field of the Invention
The present invention relates to a display system, and in particular to an error diffusion method and an apparatus thereof for a display system which are capable of preventing errors of pixels in a certain display regions from affecting pixels of other display regions on a PDP (plasma display panel) device or other display devices.
2. Description of the Prior Art
Generally, in order to implement a gray-level on a PDP (plasma display panel) device or other display devices, an error diffusion algorithm is applied to an error diffusion method and an apparatus thereof for a display system.
When there is an error in a gray-level, the error diffusion algorithm is used in order to implement visually the gray-level having the error on a display device. Herein, each pixel transmits its error to surrounding pixels, a gray-level having errors in wide regions can be visually implemented. Typically, a Floid-Steinberg algorithm is widely used.
In the Floid-Steinberg algorithm, a gray-level is implemented by multiplying a coefficient by an error value between three pixels placed the upper horizontal line and a left pixel centering around a present pixel and adding an error value of the present pixel in accordance with a carry occurrence. It is widely used for displaying of a gray-level having an error. Herein, the coefficient multiplied by an error value between three pixels in the upper horizontal line and a left pixel centering around the present pixel is an optimum value determined by considering visual characteristics of human body. The Floid-Steinberg algorithm will be described with reference to accompanying FIG. 1.
FIG. 1 is a block diagram illustrating an error diffusion applying the Floid-Steinberg algorithm.
As depicted in FIG. 1, a pixel 5 illustrates an error of a present pixel, and a pixel 1˜a pixel 4 illustrate errors of surrounding pixels.
An accumulated error of the present pixel is calculated by multiplying a coefficient by the pixel 1˜the pixel 4 as the errors of the surrounding pixels and adding the pixel 5 as an error of the present pixel. Herein, when a carry occurs, a gray-level to be displayed is varied.
However, in the above-mentioned Floid-Steinberg algorithm, errors of the present horizontal line pixels may be transmitted to pixels in a next horizontal line, in the worst case, because errors of pixels on the first line on a screen may affect errors of the last line pixels, an abnormal gray-level occurs on the screen. In more detail, a pattern on the screen is divided into figures having various shapes. For example, when regions divided into a vehicle, sky and people, etc. are displayed on one screen, an error of pixels in a vehicle region may affect bad influence to a gray-level implement of pixels in a people region placed far away from it on the screen.
In addition, because the Floid-Steinberg algorithm respectively performs an error diffusion by R (red), G (green), B (blue), a severe noise may occur. In more detail, when an error of RGB cells on the first horizontal line is different each other, the error is transmitted to the last horizontal line, a carry occurrence of the RGB cells on the last horizontal line is differed, if pixels of the last line are gray-level, on the actual screen a color can be shown. Accordingly, due to the above-mentioned problems, the Floid-Steinberg algorithm can not be used for a present display device required to have a high picture quality.